A loader is a type of tractor, usually wheeled, sometimes on tracks.
Such heavy equipment machine usually has a front-mounted square wide bucket connected to the end of two arms to scoop up stockpiled material from the ground or move it from one place to another.
It is commonly used in construction to move aside or load materials such as asphalt, demolition debris, dirt, gravel, raw minerals, etc.
into a dump truck or an open trench excavation.